The real question is: should the court order such an action, and under what conditions?
Analogy alert: GS mistakenly sends me a letter by physical mail, then asks the post office (or asks a judge to order the post office) to send a mailman round, break into my house, and retrieve the letter. That clearly won't happen; worst case is that the judge would order me to surrender the letter. In case of email, is Google (under their terms & conditions and the letter of the law) allowed to "break into" my mailbox and remove the offending letter? And should they be?
You analogy would be better if the mail had been left in the mailbox, which is regulated by the USPS and Federal Law, and which the postman has rights to access.
So it would be more like:
GS sends you a letter by mistake. They get a court order to order the USPS to remove it from the mailbox that they put in it, which happens to be yours. The postman then looks at the contents of the mailbox, verifies it is still there, and then removes it, sending it back to the sender or as otherwise directed by the courts. If, however, you checked your mail and took the mail out and into your house, then there is nothing for the USPS to do - it is no longer in the mailbox. If, however, you keep all your mail in your mailbox then the USPS would be within their ability to remove it from the mailbox.
So, to keep all your e-mail on Google's servers (or any ISPs servers) opens up the opportunity for this to happen. To keep the opportunity from happening then you need to download your e-mail from anyone else's servers and store it locally, deleting it from the providers servers after you have your local copy.
Alternatively, you can rent your own server and host your own e-mail server; but then you get into another situation in which the service you are renting from may be required by the courts to turn over the server to the courts, or get shutdown and you've now lost everything except what you had backups for. And yes, that has happened where the FBI shutdown a hosting provider and took all the servers in order to get to one of their clients; everyone else was screwed for a while.